A 6-year cohort study conducted by researchers from Japan, comprising nearly 39,000 older adults found that people living in rental flats and owner-occupied detached houses face higher risks of cardiovascular death compared with those in owner-occupied flats. The study attributes to the increased risk to colder, less stable indoor temperatures in these housing types and suggests that improving housing quality to address these issues could lower cardiovascular mortality, particularly among men.
Where we live can shape how long we live. Growing evidence shows that the quality of housing affects the risk of cardiovascular diseases (CVDs). In 2018, the World Health Organization (WHO) issued the Housing and Health Guidelines, noting that CVDs, such as stroke and heart disease are more common in cold homes. The report emphasized that exposure to cold raises blood pressure, a known contributor to CVD risk. In Japan, the Cardiovascular Disease Clinical Practice Guidelines released in 2024 also recognized housing as a social environmental factor influencing cardiovascular health.
Now, researchers at Institute of Science Tokyo (Science Tokyo), Japan, provide further evidence of clear differences in CVD risk depending on housing status. In a study published in Volume 3, Issue 2 of the journal BMJ Public Health on September 08, 2025, they report that people living in rental flats and owner-occupied detached houses face a higher risk of death from CVD, compared with those in owner-occupied flats.
The study was led by Assistant Professor Wataru Umishio from the Department of Architecture, Science Tokyo, in collaboration with colleagues from Science Tokyo's Graduate School of Medical and Dental Sciences, Hamamatsu University School of Medicine, Nihon Fukushi University, and Chiba University.
The findings are based on a 6-year cohort study of 38,731 older adults in Japan, with an average age of 73.6 years. Researchers linked participants' housing and tenure types—including owner-occupied detached houses, owner-occupied flats, rental detached houses, and rental flats—to official records of deaths from cardiovascular causes such as acute myocardial infarction, arrhythmias, heart failure, and strokes.
One explanation, the researchers note, lies in structural differences between housing types that affect indoor thermal conditions. Detached houses, exposed to the outdoor environment on all sides, are more vulnerable to low and fluctuating indoor temperatures, unlike flats, which are insulated by neighboring units. Previous studies in Japan have shown that detached houses tend to have cold and unstable indoor temperatures, both of which can raise blood pressure and increase its variability.
Men were most at risk, likely because they generally have higher blood pressure than women. According to the Japanese Society of Hypertension Guidelines, men in their 60s and 70s tend to have higher systolic blood pressure than women of the same age.
Poor housing quality in rental flats was identified as another factor. Many rental properties have inferior insulation, partly due to the "split incentive" problem, where landlords have little motivation to invest in improvements that mainly benefit the tenants. National surveys show that just 15% of rental homes in Japan have double window sashes or double-glazed windows, compared with 38% of owned homes.
The researchers suggest that improving insulation and keeping indoor temperatures above the WHO-recommended 18 °C could lower cardiovascular deaths, particularly among older adults and men. For Japan's aging population, safe and warm homes are a critical part of public health.
"Such initiatives for promoting the adoption of high-quality housing could contribute not only to improving cardiovascular health but also to enhancing planetary health by mitigating climate change through reduced energy consumption," says Umishio.
